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CONTENTS
Volume 29, Number 2, August 2019
 

Abstract
As a regenerated turbulent wind field process, wind tunnel test has proven to be a promising approach for investigating the transmission tower-line system (TTLS) performance in view of experimental scaled models design, simulation techniques of wind field, and wind induced responses subjected to typhoon. However, the challenges still remain in using various wind tunnels to regenerate turbulent wind field with considerable progress having been made in recent years. This review paper provides an overview of the state-of-the-art of the wind tunnel based on active or passive controlled simulation techniques. Specific attention and critical assessment have been given to: (a) the design of experimental scaled models, (b) the simulation techniques of wind field, and (c) the responses of TTLS subjected to typhoon in wind tunnel. This review concludes with the research challenges and recommendations for future research direction.

Key Words
transmission tower-line system (TTLS); wind tunnel test; experimental scaled models; wind induced response; typhoon

Address
Xianying Li, Hongtao Wu, Biao Zhao: College of Mechanical and Electrical Engineering, Nanjing University of Aeronautics and Astronautics, No. 29 Yu Dao Street, Nanjing 210016, P.R. China
Yu Yao: College of Aerospace Engineering, Nanjing University of Aeronautics and Astronautics,
No. 29 Yu Dao Street, Nanjing 210016, P.R. China
Bin Chen and Tao Yi: State Grid Fujian Electric Power Research Institute, No. 257 Wu Si Road, Fuzhou 350007, P.R. China;
State Grid Cultivating Laboratory of Wind Resistance and Disaster Mitigation under Severe Typhoon Environment,
No. 257 Wu Si Road, Fuzhou 350007, P.R. China




Abstract
This paper provides a simple numerical method to determine the optimal parameters of tuned mass damper (TMD) and viscoelastic dampers (VEDs) in frame structure for wind vibration control considering the soil-structure interation (SSI) effect in frequency domain. Firstly, the numerical model of frame structure equipped with TMD and VEDs considering SSI effect is established in frequency domain. Then, the genetic algorithm (GA) is applied to obtain the optimal parameters of VEDs and TMD. The optimization process is demonstrated by a 20-storey frame structure supported by pile group for different soil conditions. Two wind resistant systems are considered in the analysis, the Structure-TMD system and the Structure-TMD-VEDs system. The example proves that this method can quickly determine the optimal parameters of energy dissipation devices compared with the traditional finite element method, thus is practically valuable.

Key Words
viscoelastic damper; tuned mass damper; soil structure interaction; genetic algorithm; optimization

Address
Xuefei Zhao and Han Jiang: Nanjing Yangtze River Urban Architectural Design Co., LTD., Nanjing 210000, China
Shuguang Wang: College of Civil engineering, Nanjing Tech University ,Nanjing 210000, China

Abstract
The tapered and set-back type of unconventional designs have been used earlier in many buildings. These shapes are aerodynamically efficient and offer a significant amount of damping against wind-induced forces and excitations. Various studies have been conducted on these shapes earlier. The present study adopts a hybrid approach of turbulence modelling i.e., Detached-eddy Simulation (DES) to investigate the effect of height modified tapered and set-back buildings on aerodynamic forces and their sensitivity towards pressure. The modifications in the flow field around the building models are also investigated and discussed. Three tapering ratios (T.R.= (Bottom width- Top width)/Height) i.e., 5%, 10%, 15% are considered for tapered and set-back buildings. The results show that, mean and RMS along-wind and across-wind forces are reduced significantly for the aerodynamically modified buildings. The extent of reduction in the forces increases as the taper ratio is increased, however, the set-back modifications are more worthwhile than tapered showing greater reduction in the forces. The pressure distribution on the surfaces of the buildings are analyzed and in the last section, the influence of the flow field on the forces is discussed.

Key Words
aerodynamic modification; tapering ratio; set-back; DES model; flow field

Address
Ashutosh Sharma and Hemant Mittal: Centre of Excellence in Disaster Mitigation and Management, Indian Institute of Technology Roorkee, Roorkee-247667, India
Ajay Gairola: Department of Civil Engineering, Indian Institute of Technology Roorkee, Roorkee-247667, India

Abstract
The maximum along-wind displacement of a considerable amount of building under simulated wind loads is computed with the aim to produce a simple prediction model using multiple regression analysis with variables transformation. The Shinozuka and Newmark methods are used to simulate the turbulent wind and to calculate the dynamic response, respectively. In order to evaluate the prediction performance of the regression model with longer degree of determination, two complex structural models were analyzed dynamically. In addition, the prediction model proposed is used to estimate and compare the maximum response of two test buildings studied with wind loads by other authors. Finally, it was proved that the prediction model is reliable to estimate the maximum displacements of structures subjected to the wind loads.

Key Words
wind simulation; dynamic analysis; maximum displacement; multiple regression; spectral density

Address
Omar Payán-Serrano, Edén Bojórquez and Alfredo Reyes-Salazar: Facultad de Ingeniería, Universidad Autónoma de Sinaloa, México
Jorge Ruiz-García: Facultad de Ingeniería Civil, Universidad Michoacana de San Nicolás de Hidalgo, México

Abstract
One of the most important factors in tall buildings design in urban spaces is wind. The present study aims to investigate the aerodynamic behavior in the square and triangular footprint forms through aerodynamic modifications including rounded corners, chamfered corners and recessed corners in order to reduce the length of tall buildings wake region. The method used was similar to wind tunnel numerical simulation conducted on 16 building models through Autodesk Flow Design 2014 software. The findings revealed that in order to design tall 50 story buildings with a height of about 150 meters, the model in triangular footprint with aerodynamic modification of chamfered corner facing wind direction came out to have the best aerodynamic behavior comparing the other models. In comparison to the related reference model (i.e., the triangular footprint with sharp corners and no aerodynamic modification), it could reduce the length of the wake region about 50% in general. Also, the model with square footprint and aerodynamic modification of chamfered corner with the corner facing the wind could present favorable aerodynamic behavior comparing the other models of the same cluster. In comparison to the related reference model (i.e., the square footprint with sharp corners and no aerodynamic modification), it could decrease the wake region up to 30% lengthwise.

Key Words
tall building; shape optimization; wind effects; aerodynamic modification; wake region; wind tunnel simulation

Address
Abdollah Baghaei Daemei: 1Department of Architecture, Rasht Branch, Islamic Azad University, Rasht, Iran
Seyed Rahman Eghbali: Department of Architecture, Imam Khomeini International University, Qazvin, Iran


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